Green Hydrogen Peroxide (H2O2) monopropellant with advanced catalytic beds

The project has focussed on developing & testing new catalytic beds integrated into a miniature thruster - comparable to the size of a euro-cent coin.The developments, carried out by a small consortium led by Austrian SME, Aerospace Technology GmbH, have succeeded in convincingly demonstrating desired levels of improved thruster performance using advanced catalytic beds, with Hydrogen Peroxide (H202) as the low-toxicity, "green" propellant.

The Challenge

Monopropellant thrusters using hydrazine (N2H4) are commonly used on a variety of spacecraft and satellites. However, hydrazine is a highly toxic and dangerously unstable substance. Importantly, its use as a propellant has been compromised by stringent laws to protect personnel who have to work with substances which are highly toxic and carcinogenic.Recently, much more benign, low toxicity (“green”) storable liquid propellants have therefore attracted considerable attention as possible replacements for hydrazine. This is due to the significant increase in the costs of production, storage & handling of toxic propellants, and has set the stage for the search for green replacement propellants.Hydrogen peroxide (H2O2) is one of the most attractive replacements, not only since it is non-toxic and non-carcinogenic, but also due to its many advantageous properties, such as its high density and relatively low cost. From a financial standpoint, H2O2 also promises significant cost savings due to the drastic simplifications in health & safety protection procedures during the production, storage and handling of the propellant.
Ceramic monolithic catalyst cell matrix
These advantages are of special relevance in low or medium thrust rocket engines for small missions, which offer strong potential as profitable opportunities for focussed SMEs.The most significant technological challenge in the realisation of viable H2O2 monopropellant thrusters is the development of effective, reliable, long-lived catalytic beds, characterised by:
  • fast and repeatable performance,
  • insensitivity to poisoning by the stabilizers and impurities in the propellant,
  • possibly not requiring preheating for efficient operation, and
  • capable of sustaining the large number of thermal cycles imposed by typical mission profiles.
To this end, the project has focussed on developing & testing new catalytic beds integrated into a small thruster. Extensive tests have enabled characterisation of both catalytic and propulsive performance in terms of: decomposition temperature and efficiency; thrust, specific impulse, number and repeatability of short duration (2-5s) impulses; and resistance to poisoning and thermal cycling.

Achievements

Schematic cutaway showing advanced thrusters internal design and location, above nozzle, of the monolithic catalyst cell matrix.
Note size of thruster compared to 1 EuroCent coin.
The project has succeeded in convincingly demonstrating desired levels of improved thruster performance using advanced catalytic beds. These are considered capable of better meeting typical operational requirements of monopropellant rocket engines, and represent significant progress in the state-of-the-art in this sector. They are expected to open the possibility for industrial development & application of H2O2-fuelled thrusters in Europe.Developing and using an engineering model miniature thruster, it has been shown that the use of monolithic catalysts results in a highly efficient decomposition (up to 99%) of H2O2. Performance evaluations have verified a vacuum thrust range between 150 to 900 mN at a specific impulse of 153s. Analytic evaluations of these results show the potential to obtain a specific impulse of 164s and a thrust of nearly 1N.Overall, the system is considered as very suitable for use in small satellites. It has been experimentally verified that the catalyst lifetime is sufficient to decompose 1.2kg of H2O2 propellant.In performance terms, this translates into:
  • Total impulse of about 1900 Ns.
  • deltaV = 20 m/s for a 100 kg satellite.
  • Orbit maintenance of a sun synchronous satellite (100 kg) for one year
  • Drag compensation for one year for a satellite in a 400–500 km orbit
Schematic structure of miniature thruster with catalyst chamber for testing of monopropellant
The project has been able to explore and carefully document, in particular, the behaviour of the monolithic structure of the catalyst, as the propellant is progressively decomposed.This has led to the conclusion that if the sole limiting factor on lifetime of the catalyst – related to cracking of the monolith – can be overcome, then experimental results indicate a total useful lifetime sufficient to decompose up to 5.5kg of H2O2, corresponding to a total impulse of 7500Ns.At the stage of development achieved by the end of the project, the thruster, incorporating the advanced catalytic bed, has been estimated as capable of reaching Technology Readiness Level (TRL) 5 within 2 years. That is, able to move from preparatory R&D, to being assessed for technology readiness and qualification as a flyable product.

Project Details

Green Hydrogen Peroxide (H2O2) monopropellant with advanced catalytic beds.
LET-SME contract no. 18901

  • Year of award: 2005
  • Amount of funding: €200000
  • Completion: July 2006

SME Prime contractor:
Aerospace Technology (Mechatronic Systemtechnik) AG
Villach, Austria

Cooperating research partners :

  1. CNRS – LACCO, Université de Poitiers
    Poitiers, France
  2. ARC Seibersdorf Research GmbH
    Seibersdorf, Austria
Copyright 2000 - 2014 © European Space Agency. All rights reserved.